The use of the Resophonic Guitar has increased in popularity in many genres of music including Bluegrass, Folk, Country, Country Rock, and Rock and Roll. A popular style of resophonic guitar playing uses a bar, usually made of steel or brass and raised strings. The bar (or slide as it is commonly referred to) is held against the strings producing a slurring sound. The strings do not contact the fret board as is the case in traditional guitar playing. Also the instrument is generally held in a horizontal position as opposed to the usual vertical position that is popular in traditional guitar playing. This style of playing is similar to Hawaiian Steel Guitar or Lap Steel Guitar.
The resophonic guitar is usually tuned to an open chord, the popular tunings being Open D (DADF#AD) and Open G (GBDGBD). It would be a tremendous advantage if an instrument could be instantly retuned to either of these tunings with a single flip of a toggle lever during a song. Of course in doing so, many factors would have to be addressed. For convenience, the example of tuning between Open D and Open G tunings will be used for this patent application. It must be noted that there are many other tunings that lie within the scope of this invention. It must also be noted that although the resophonic guitar is highlighted in this application, the invention will work on many other types of acoustic and electric guitars as well as many other types of string musical instruments.
Manually retuning the guitar from one open tuning to another during a performance would not be practical. It would take many minutes to tune and retune the instrument. So if a performer would like to be able to switch from one tuning to another, traditionally two guitars would have to be used.
The open D tuning consists of the strings tuned to these specific notes: The 6th string is D (which is stretched to about 21 pounds in tension), the 5th is A (36 pounds), 4th string is D (32 pounds), 3rd is F# (32 pounds), 2nd is A (18 pounds) and 1st is D (24 pounds). The total tension of all string applied to the guitar when tuned to open D is about 163 pounds.
The open G tuning consists of the strings tuned to the following notes; 6th string is G (38 pounds), 5th string is B (44 pounds), 4th string is D (32 pounds), 3rd string is G (36 pounds), 2nd string is B (22 pounds) and the 1st string is D (24 pounds). The total pounds applied to the guitar when tuned to an open G chord are about 196 pounds. The change of tension of the strings between Open D and Open G tuning totals approximately 33 pounds. A mechanical device would have to be developed to accurately and simultaneously retune this tension differential.
The following tuning charts are helpful in visualizing and comparing the Open D tuning with the Open G tuning
OPEN D TUNINGSTRINGLBS1ST STRING D242ND STRING A183RD STRING F#324TH STRING D325TH STRING A366TH STRING D21
OPEN G TUNINGSTRINGLBS1ST STRING D242ND STRING B223RD STRING G364TH STRING D325TH STRING B446TH STRING G38
In reviewing the charts, it is apparent that the 4th string D and 1st string D are common between the G and D tunings One might think that this would facilitate the rapid transition tuning between D and G tunings. However, as the 6th string D tension is increased to G, the 5th string A tension is increased to B, the 3rd string F# tension is increased to G and the 2nd string A tension is increased to B, a slight flexing or bending motion takes place in the instrument. This bending motion is much like how a bow deforms as an archer pulls the bow string back. Unlike the archer and bow, the deformation of the instrument is not as visually apparent. However it does affect the pitch of the common notes of the 1st and 4th strings. As the instrument bends inward (switching from D to G), the common strings slacken slightly which audibly lowers their pitch. Therefore it would be highly desirable that the device be able to automatically compensate for this drop of pitch incurred on the common strings.
As Resophonic guitars can be very expensive, it would be preferable that the invention mount to the instrument in such a manner as to not degrade or permanently alter the instrument.
It would be highly desirable that the invention also fit into the guitar case.
It would be important that the invention not detract from the aesthetic of the instrument.
It would be desirable that the invention be quickly tunable without the use of tools such as tuning wrenches.
Because the instrument is generally played acoustically, it is highly desirable that no electric power or any other alternative power be required to perform the tuning function.
Smooth, musical transition between tunings should be accomplished.
Because the instrument is acoustic and is very often amplified or recorded by the use of sensitive microphones, it is essential that the invention operate quietly and smoothly.
By the use of descriptions and figures, the following pages will show how embodiments of the present invention accomplish these objectives.